Maximum number of concurrent pipeline runs. 0 means unlimited. Excess runs are queued.
MAX_CONCURRENT 1The MAX_CONCURRENT clause limits the number of pipeline runs that this schedule may have executing simultaneously. The value must be a non-negative integer; setting it to 0 removes the concurrency cap entirely. When a cron tick fires but the concurrent-run limit has already been reached, the new run is placed in a queue and dispatched as soon as a running instance completes. When omitted, the default is 1, ensuring strictly sequential execution. This clause interacts with PRIORITY to determine the order in which queued runs are dispatched when multiple schedules compete for execution slots.